EcologicalStudieson JapaneseEncephalitisVirus. Isolation of JapaneseEncephalitisVirus from MosquitoesCollected in Nagasakiand Kagoshimadistricts, Japan, in 1965.

Continual survey in Nagasaki prefecture were established at Kuromaru village since last year. In this season, 13 places in Nagasaki prefecture and the suburbs of Taniyama city, Kagoshima prefecture, were selected additionally for the collection of mosquitoes. The hibernated female of Culextritaeniorhynchus collected in Nagasaki destrict from 16th March to 30th April in this season have been made, however, no virus could be isolated. During the period from 30th May to 6th September, 47 of 56 strains were isolated from Culextritaeniorhynchus mosquitoes, 5 of them from Culex vishnui and 2 of them from Culexpipiens pollens respectively. In addition, 2 strains regarded as Japanese encepha- litis virus (hereinafter referred to as JE) were isolated from Aedes vexans. The first isolation of JE virus from Culex tritaeniorhynchus mosquitoes was made on 30th May in Nagasaki area, while in Kagoshima area it was made on 17th June. Comparing the patterns of JE virus isolations, it was demonstrated that there were remarkable difference of JE virus dissemination by area and by periods. The ecological investigation of JE viruses has been stated on the bases of the JE virus isolations from mosquitoes, the rising of haemagglutination inhibition antibodies in swine sera and the occurrences of human encephalitic cases.